The use of pneumatic guns, for example, paintball guns, has grown substantially over the past 20 years. Typical pneumatic and pneumatic paintball guns control and direct the expansion of compressed gas to accelerate a projectile through a cylindrical barrel. Paintball weapons accelerate a projectile that strikes and deposits paint on a target. The weapons are used to mark an opposing combatant to simulate being shot without substantial harm to the combatant. This simulation is useful to train police, military personnel and for recreational, competitive games and simulation. In such simulations and games, weapons that can fire at a high rate of fire while retaining accuracy increase the successful marking of other opposing combatants and more accurately simulate conventional firearms.
These types of weapons are not limited to paintball or BB guns. These weapons can also be used to inflict lethal or non-lethal force through the use of conventional or rubber bullets, beanbags, and projectiles filled with irritants, pungent chemical or other disorienting means. Furthermore, the guns can be used to deliver prizes (tee shirts, baseballs, etc.) at sporting events.
One problem with known pneumatic guns is that they use a mechanical piston or bolt to seal the firing chamber after a projectile has been loaded into the firing chamber. This mechanical piston or bolt may damage the projectiles before they are even fired. FIG. 1 shows a portion of a typical barrel assembly for a pneumatic gun. The barrel 10 has a firing chamber 12 from which a projectile 22 is fired out of the barrel 10 through the opening 14. A piston or bolt 16 is used to load projectiles into the firing chamber and to block a second opening 18 in the firing chamber 12. In operation, when the firing sequence is initiated, propellant such as air or a gas is introduced into the firing chamber 12 through an inlet valve 20. The pressure expansion caused by the propellant causes the projectile 22 to overcome the projectile restraint 24 and be expelled through the opening 14. To reload, the piston or bolt 16 is retracted and another projectile from the hopper 24 is moved into the firing chamber as the piston or bolt 14 is moved back to seal the second opening 18.
The physical movement of the piston or bolt 16 causes various problems. First of all, the piston or bolt 16 may rub against the projectiles as it opens and closes and introduce defects into the projectile. The defects may change the flight characteristics of the projectile which can affect the accuracy of the gun. Furthermore, a partially chambered projectile may become jammed when the piston or bolt 16 is moved to seal the opening 14. This may even lead to the rupture of the projectile inside the gun. In addition, the piston or bolt 16 may become jammed due to a mechanical failure thereby rendering the gun inoperable.
Thus, there is a need for a new barrel assembly which overcomes the problems described above with known barrel assemblies.
Hence, an improved barrel assembly which reduces the problems associated with loading projectiles using a mechanical piston or bolt would be advantageous.
Some of these problems are alleviated in guns with multiple projectiles in a single chamber, but then have further problems associated with reloading. This type of gun is comprised of a stack of alternating projectiles and powder. The projectiles radially expand to seal the explosion from disturbing the next charge. Each round is in a different part of the barrel stack and has a different effective barrel length which decreases consistency and accuracy. Also, the breach end of the barrel is permanently sealed. This forces the user to reload the weapon through the muzzle or the barrels may be disposable or must be reloaded back at the factory. This is very inconvenient and makes sustained automatic fire difficult to achieve.